60 - 120hz hum when recording with USB Microphone

I teach photography and do a lot of screen recordings narrating what I'm demonstrating with a Logitech USB Microphone. I've done this since I purchased the computer without incident until recently.

Now, my recordings have a rather loud hum throughout. The sound is one that one might experience if their power supply were starting to go bad.

The first thing I did was check my recordings without the power supply plugged in and the recordings are clean.

Next, I cleaned all the contacts on the MagSafe connector without any results. I then replaced the power supply without any results.

So, the hum is only present when the power supply is plugged into the computer and it doesn't matter if the supply is new or used. I've tried numerous mic's to see if one was better than my preferred mic and they all do it.

Any suggestions appreciated.